Problem: Remote T-Sql debugger from SSMS SQL 2008 fails  with one of the following issue:

Could not attach to SQL Server process on 'MyInstance'.The RPC server is unavailable
Unable to start T-SQL debugging. Could not attach to SQL Server process on 'MyInstance'.

So, you are not able to remotely connect in SQL Server Management Studio to your development server in  SQL Server 2008

Troubleshooting to do: All tests below are not only for the RPC issue but also for others issues like authentication.

Test 1: When you locally connect to the same instance the issue is not reproduced

Test 2: Check if  TCP 139, TCP 445, UDP 137 and UDP 138   are open from both side (server and client) (e.g.: Configuring the Transact-SQL Debugger )

Test 3:
Check if SQL management Studio is lauched with "Run an administrator..."

Test 4:
  Check if SQL service account can connect to the client machine. When you are using T-SQL debugging, SQL service account will communicate with the machine host Management Studio.It's an additional  reason to set up SQL service with domain account 

Test 5: Check if SSMS and SQL server service are in the same domain. if not, set up the same account and password that SQL server is using.

Test 6:
 Check if your domain account is sysadmin.

Test 7: Check if Kerberos is enable correctly and SPN are ok for your instance.
- The SQL Network Interface library was unable to register SPN
- SQL Server 2008 connectivity issue : cannot generate SSPI context

Test 8: Check from server side that the service below are started
- TCP/IP NetBIOS Helper
- Remote Registry
- RPC Service


Michel Degremont | Premier Field Engineer - SQL Server Core Engineer |